Steel and Sustainability II: Recovery
This second article addresses the concepts of recovery. It follows Steel and sustainability I: Integration (see CA, January 2004). This time, the unique nature of steel as a building material (and its infinite life) is reviewed in terms of recovery. Recovery implies the reuse of an existing structure or the recycling of steel products, and extending the sustainable life of a structure and the material through multiple recovery cycles–thus honouring the “from cradle to cradle” concept. Reusing steel involves dismantling a structure so it can be rebuilt elsewhere, or reusing steel members and elements from a demolition site for a new building. Recycling can also mean taking the steel members from an old structure or from defunct automobiles, appliances and industrial wastes, and creating new steel by re-melting the material in a furnace. Recovery strategies should be considered not only at the end of a structure’s life, as is commonly done, but they should be integrated from the onset during the conceptual phase.
Two contemporary technologies are used to produce steel: the basic oxygen furnace (BOF) and the electric arc furnace (EAF), which integrate old steel to make new differently. The BOF consistently uses 20 to 25% of recycled content (up to a maximum of 35%), and the EAF consistently uses 90% of recycled content (up to nearly 100%, in some cases). It is the EAF, which yields products such as structural beams, steel plates and reinforcement bars. To obtain a recycled content value of steel products, the Steel Recycling Institute provides a fact sheet and a calculation method associated with the LEED requirements on their website (www.recycle-steel.org/leed). A mill test, or the results from a coupon test, confirms the quality of the steel, its weldability, and its strength. A coupon consists of a physical cutout from the reused steel member, generally a rectangle of about 1 foot long by 2* or 3* wide. If the only concern is weldability, only a chemical test is required.
Today, reused steel can be obtained either from a warehouse, a fabricator’s yard or more likely, from a current or future demolition site where a structural engineer may make it a habit of tracking potential projects for opportunities for steel reuse. With regards to the reuse of joists, the best chance is to have good contacts with demolition crews before a building is torn down, and make sure the joists are handled with care. Throughout the project procurement method– one should also consider asking what is available to the fabricators involved in the project (possibly another project team member at the early stages of the integrated design process). The following four projects are examples where steel is being reused.
The ROM donates old steel to the University of Toronto at Scarborough (date of reused steel: 1970s)
In 2003, Dunlop Architects and Halsall Engineers came up with the idea that part of the material for a new Student Centre for the University of Toronto at Scarborough could come from existing sources. Halsall, who is presently working on demolishing part of the Royal Ontario Museum (ROM) in Toronto, proposed reusing girders from the ROM for the Student Centre. Since Halsall had been involved with the addition to the ROM building in the late 1970s, they had all the necessary archives for demonstrating the material quality of the steel to be reused–therefore no testing was required. However, the biggest challenge was for the architect to coordinate the transfer of donated steel from the ROM building to the University of Toronto. This administrative aspect had to be factored into a fabrication schedule and fortunately, amounted to an approximate savings of 18 tons of steel.
An old warehouse becomes Baie-Saint-Paul’s new Town Hall (date of reused steel: 1960s)
Anne Carrier Architectes created the required new public building for Baie-Saint-Paul from essentially an old industrial shed built in the 1960s. With the exception of one corner of the building, which once endured a fire, all of the steel was reused. Several sections tested from different locations revealed that the yield strength employed at the time of construction could be taken by calculating the resistance of the members based on current standards, and that welding would not be a problem. There appeared to be several sources of steel–one of which originated in Britain–which prompted the engineer to test in different locations.
The Eaton building in Montreal becomes Le Complexe les Ailes (date of reused steel: 1920s-1950s)
In 2002, Lemay & Associs took the Eaton building in Montreal and refurbished it into the new and elegant Complexe les Ailes. Although part of the structure was gutted to create an ovoid atrium, much of the structure was reused. Most of the steel, which dates from several eras, ranging from the ’20s to the ’50s, could be reused–as concluded by the engineering firm Pasquin St-Jean, which had samples of the steel tested for its yield strength and carbon content. The original roof structure was reinforced by adding extra joists between the existing ones to create an additional top floor.
Old Angus beam gets second life in the new Chapiteau des Arts du Cirque (dates of reused steel: several)
In 2003, Le Cirque du Soleil retained the joint proposal by Schme, and Jodoin, Lamarre, Pratte & Associs, and the structural engineer Martoni Cyr et Associs for their new Chapiteau. In this project, the engineers only needed a chemical test to verify the weldability of the steel, relying on a lower allowable yield stress for unidentified steel as permitted in the steel construction standard. The reused steel for this project was purchased through a new acquiring process, as this was a relatively ‘non-standard’ order.
Applying LEED to steel recovery
With regards to LEED rating for recovered steel, there are five applicable credits in the Materials & Resources category.
Credit 1: Building Reuse (2 possible points) is used when considerations are made for steel structures that can be easily adapted to be modified and reinforced.
Credit 2: Construction Waste Recycling (2 possible points) is used where LEED recognizes both types of waste: demolition and ‘by-product’ of construction.
Credit 3: Resource Reuse (2 possible points) is allocated for salvaged or refurbished components.
Credit 4: Recycled Content (2 possible points) is used to calculate recycled content: post-consumer, and post-industrial.
Credit 5: Local/Regional Materials (2 possible points) allocates one point if the place of steel fabrication (where steel is formed into its final shape) is within 500 miles of the project site, and an additional point if the raw materials for the production of that steel are extracted or harvested within 500 miles of the project site.
The future of steel recovery is very green, both in terms of recyclability and reuse. The industry catering to recycling has a strong history, which can only continue to contribute to a future of possibilities. The construction industry is quickly beginning to understand the concepts of reusing steel. For the moment, each search for reused steel requires a one-of-a-kind effort. We believe that a form of business relationship will develop between structural engineers, demolition companies, and fabricators that will contribute to the development of the reused steel industry (warehouse databases, service centers, and catalogues of future demolition sites). This process will help to offer links to the available options and strategies available to the design and construction industry.
Sylvie Boulanger is Executive Director for the Quebec Region of the Canadian Institute of Steel Construction in Montreal. Sylvain Boulanger is Principal with BoldWing Continuum Architects, and a LEED accredited professional in Surrey, B.C. A more detailed article on steel recovery, including exact formulas for achieving these LEED points can be found on the CISC website at www.cisc-icca.ca/green